Seedlings in Northern Illinois today are mostly about 2-3 inches (5-7 cm) above soil level. One month from now these plants will stand 24-36 inches (60-92cm) high. All of that above ground structure will be due to cell elongation in leaf tissue, as the ‘stem’ remains close to the ground within the tight wraps of the leaf sheaths.
Much of the above-ground growth for the first 30-40 days after seedling emergence is due to cell elongation within leaves. This not only allows the expansion of leaf blades to increase the mass of leaf tissue, but also elongation of the leaf sheaths, pushing up the plant height. Cell elongation is not only occurring in the outer tissue, but internal cells also grow in size during this time.
Cell elongation is driven by energy allowing production of cell components such as cell wall cellulose and lignin but also increase in the membranes, ribosomes, mitochondria and chloroplasts needed to drive the growth. Immature cells, before tightly constricted by deposits of solid cell walls, expand with water pressure during this growth pressure. Consequently, soil water and root development become major factors affecting the size of the corn plant during this pre-flowering stage. Root development not only affects the absorption and movement of water into these growing leaf cells but also uptake minerals needed for the general metabolism. Expansion of leaf blades during this time also increases the absorption of light driving photosynthesis, providing more energy for cell function and growth.
Multiple environment factors influence water supply to corn plants, but genetics also distinguish variety reactions to growth of the plant. Root size and growth pattern affect water and mineral uptake. Structure of vascular tissue from roots to leaves affect efficiency of water movement. Number and activity of stomata in leaves affect the evaporation of water from leaves. Efficiency and number of chloroplasts within the cells affect the transmission of light energy to carbohydrates, mitochondrial numbers and efficiency affect the change of this energy into ATP for use in the formation of proteins and other products needed for cell growth. Translation of chromosomal DNA to RNA that moves to ribosomes where the codes for specific amino acids are strung together for specific proteins, some of which are used as enzymes driving production of cell structure components. A large number of those 30-40000 corn genes must be participating in that early growth of a corn plant.
It is easy to be amazed during this time of the year to watch the rapid growth within a corn field, but we are only seeing a tiny fraction of what is happening within those plants.
Visit us at the ASTA in Chicago, Dec 9-12 (booth G207)
About Corn Journal
The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.